Compression molding machine

ABSTRACT

A compression molding machine includes a wheel mounted for rotation around a horizontal axis and a plurality of angularly spaced molds disposed around the wheel. Each of the molds includes a first mold segment and a second mold segment disposed radially outwardly of the first mold segment. Each of the second mold segments is movable radially with respect to the associated first mold segment between a radially inner closed position with the first mold segment for compression molding a plastic article, and a radially outer open position spaced from the associated first mold segment for removing a molded article from the mold and placing a mold charge into the mold.

This application is a division of application Ser. No. 11/109,374 filedApr. 19, 2005 now U.S. Pat. No. 7,331,777.

The present disclosure is directed to a machine for molding plasticarticles, such as closure shells or sealing liners within closureshells.

BACKGROUND AND SUMMARY OF THE INVENTIONS

Machines for compression molding closure shells, or compression moldingsealing liners within closure shells, typically include a turret orcarousel that rotates around a vertical axis. A plurality of molds areprovided around the periphery of the carousel, in the form of male andfemale mold sections that are aligned along vertical axes parallel tothe axis of rotation. Cams drive one or both of the mold sections ofeach pair between an open position, in which a molded part is strippedfrom the male mold section and a charge of plastic material is placed inthe female mold section, and a closed position in which the male andfemale mold sections are brought together to compression mold the shellor liner. In a liner machine, premade shells are placed in a nest whenthe mold sections are open, and a charge or pellet of liner material isplaced within the shell before the molds are closed. U.S. patents thatillustrate machines of this type for compression molding plastic closureshells include U.S. Pat. Nos. 5,670,100, 5,989,007, 6,074,583 and6,478,568. U.S. patents that illustrate machines of this type forcompression molding sealing liners within closure shells include U.S.Pat. No. 5,451,360.

Although vertical axis carousel-type machines of the noted type haveenjoyed substantial commercial acceptance and success, innovationremains desirable. In particular, in vertical axis carousel-typemachines, the mold forces and the weight of the rotating equipment areparallel to the vertical axis of rotation, creating a bending momentwith respect to the axis of rotation and the bearings and shaft thatsupport the carousel. Carousel-type machines also require a substantialamount of valuable floor space in a manufacturing facility. It is ageneral object of the present disclosure, in accordance with one aspectof the disclosure, to provide a method and apparatus for compressionmolding plastic articles, such as plastic closures and plastic linerswithin closure shells, which reduce the forces applied to the supportframe and bearings, reduce maintenance requirements and the amount ofenergy needed to operate the machine, and/or reduce the amount of floorspace required per machine.

The present disclosure involves a number of aspects or inventions, whichmay be implemented separately from or in combination with each other.

A compression molding machine in accordance with a first aspect of thepresent disclosure includes a wheel mounted for rotation around ahorizontal axis and a plurality of angularly spaced molds disposedaround the wheel. Each of the molds includes a first mold segment and asecond mold segment disposed radially outwardly of the first moldsegment. Each of the second mold segments is movable radially withrespect to the associated first mold segment between a radially innerclosed position with the first mold segment for compression molding aplastic article, and a radially outer open position spaced from theassociated first mold segment for removing a molded article from themold and placing a mold charge into the mold.

In some preferred embodiments of the disclosure, a cam is disposedadjacent to the wheel for moving the second mold segments radiallyinwardly and outwardly in sequence as the wheel rotates around its axis.Each of the molds may include an abutment for engagement by the secondmold segment as the second mold segment is moved radially outwardly fromthe associated first mold segment, and a stripper coupled to theabutment for stripping molded parts from the first mold segment. Therepreferably is lost motion between the second mold segment and theabutment to allow the second mold segment to clear the first moldsegment before stripping. In other embodiments of the disclosure, thestripper is operated by a cam independently of motion of the second moldsegment. Back-up springs, such as coil or fluid springs, preferably aredisposed between the first mold segments and the wheel for absorbingexcess compression force applied to the first mold segment. The moldspreferably are disposed in angularly spaced circumferential arrays onboth sides of the wheel for balancing the forces applied to the wheeland by the wheel to its rotating mechanism. Each of the molds preferablyincludes a cam-operated latch for releasably locking the second moldsegment to the first mold segment in the closed position of the moldsegments.

A compression mold for molding plastic closures or plastic liners withinplastic closures, in accordance with another aspect of the disclosure,includes at least one male mold segment having a mold core and astripper sleeve surrounding the mold core. At least one female moldsegment is aligned with the male mold segment. The female mold segmentis movable with respect to the male mold segment between a closedposition to form a mold cavity with the male mold segment, and an openposition spaced from the male mold segment for removing a molded articlefrom the cavity and placing a mold charge into the cavity. The strippersleeve is operatively coupled to the female mold segment to move overthe mold core and strip a molded part from the core as the female moldsegment is moved away from the male mold segment. The stripper sleevepreferably is coupled to the female mold segment in such a way thatthere is lost motion between the stripper sleeve and the female moldsegment to allow the female mold segment to clear the mold core beforeinitiating motion of the stripper sleeve with respect to the core. Thestripper sleeve is movable axially over the mold core in preferredembodiments of the disclosure. However, movement of the female moldsegment also could impart rotary motion to the stripper sleeve tounthread a molded closure from the mold core, for example.

A method of compression molding plastic articles, such as plasticclosure shells or plastic sealing liners within closure shells, inaccordance with yet another aspect of the present disclosure, includesproviding a wheel mounted for rotation around a horizontal axis and aplurality of angularly spaced molds around the wheel. Each of the moldsincludes a first mold segment and a second mold segment disposedradially outwardly of the first mold segment. As the wheel is rotated,each second mold segment in turn is moved radially outwardly withrespect to the associated first mold segment and a plastic mold chargeis placed between the mold segments. The second mold segment is thenmoved radially inwardly to a closed position with the first mold segmentto compression mold the article. When the second mold segment isthereafter moved radially outwardly from the associated first moldsegment, the molded article is removed from the mold prior to placementof a new mold charge between the mold segments. In one preferred methodin accordance with this aspect of the disclosure, the outward motion ofthe second mold segment is used to remove the molded article from themold.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objects, features, advantagesand aspects thereof, will best be understood from the followingdescription, the appended claims and the accompanying drawings, inwhich:

FIG. 1 is a front elevational view of a compression molding machine inaccordance with one presently preferred embodiment of the disclosure;

FIG. 2 is a side elevational view of the compression molding machineillustrated in FIG. 1;

FIG. 2A is an enlargement of a portion of FIG. 2;

FIGS. 3A-3D together form a sectional view taken substantially along theline 3-3 in FIG. 2;

FIGS. 4A-4D together form a side elevational view of the apparatusillustrated in FIGS. 3A-3D;

FIG. 5 is an enlarged view of a portion of FIGS. 3B-3C illustrating oneof the mold segment pairs;

FIGS. 6A and 6B together form a sectional view of a modification toFIGS. 3A-3D.

FIG. 7 is a front elevational view, which is similar to that of FIG. 1but illustrates a modified embodiment of the disclosure;

FIG. 8 is a partially sectioned elevational view of a modification tothe disclosure for molding sealing liners within closure shells;

FIG. 9 is a fragmentary front elevational view of a modification to themachine of FIG. 2;

FIG. 9A is a fragmentary sectional view taken substantially along theline 9A-9A in FIG. 9;

FIGS. 10A-10C are schematic diagrams that illustrate sequential stagesof operation of the embodiments of FIGS. 9-9A;

FIG. 11 is a fragmentary front elevational view of a modification of theembodiment of FIG. 9;

FIG. 12 is a fragmentary sectional view on an enlarged scale of amodification to the mold core in the embodiment of FIGS. 6A-6B;

FIG. 12A is an enlarged view of the portion of FIG. 10 within the area12A;

FIGS. 12B-12E are sectional views of components in the mold core of FIG.12;

FIG. 13A is a fragmentary sectional view that illustrates the moldcavity in the embodiment of FIGS. 6A-6B;

FIG. 13B is a fragmentary sectioned perspective view of the cavity andunderlying support in FIG. 13A;

FIG. 14 is a fragmentary schematic diagram that illustrates an apparatusfor placing mold charges into the compression molds in sequence inaccordance with another aspect of the disclosure;

FIG. 15 is a schematic diagram that illustrates operation of theapparatus for FIG. 14;

FIGS. 16, 17 and 18 are schematic diagrams that illustrate sequentialstages of operation of the placement apparatus of FIG. 14.

FIG. 19 is a fragmentary elevational view on an enlarged scale of themold charge placement mechanism of FIG. 1 in accordance with anotheraspect of the disclosure;

FIG. 20 is a top plan view of the mechanism of FIG. 19;

FIGS. 21 and 22 are sectional views of the mechanism of FIGS. 19 and 20;and

FIG. 23 is a fragmentary elevational view of a modification to the moldlock of FIGS. 3D and 4D.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-2 illustrate one presently preferred embodiment of thedisclosure in the form of a machine 20 for compression molding plasticclosure shells. Machine 20 includes a wheel 22 mounted on a shaft 24between spaced supports 26. Shaft 24 is coupled by a pulley 30 and abelt 32 to a motor 36 (FIG. 7) for rotating shaft 24 and wheel 22 arounda horizontal axis. Wheel 22 includes a hub 37 (which may be part ofshaft 24) and a support 39 extending radially from hub 37. Support 39may comprise a disk or the like, or may be in the form of a plurality ofangularly spaced radially extending support spokes 38. Each supportspoke 38 is hollow at its outer end. A rod 40 is slidably supported bysleeve bearings 42 (FIGS. 3B-3C) within the hollow outer end of eachspoke 38. A crossbar 50 is coupled to the end of each rod 40, so thatthe combination of rod 40 and bar 50 is generally T-shaped as viewedfrom the tangential direction in FIG. 1. A pair of radially spacedexternal supports 44, 46 (FIGS. 3B-3C) are provided on each spoke 38. Aplurality of angularly spaced molds 52 are disposed around the peripheryof wheel 22, preferably on both sides of the wheel. Each mold 52 isdisposed between supports 44, 46 on an associated spoke 38 and an end ofcrossbar 50 on rod 40. All of the molds 52 preferably are identical.

Each mold 52 includes a radially inner first mold section or segment 54and a second mold section or segment 56 in radially outward alignmentwith an associated first mold segment 54 (FIGS. 3B-3C, 4B-4C and 5). Inthe illustrated embodiments, the radially inner first mold segment 54 isa male mold segment, and the radially outer second mold segment 56 is afemale mold segment, although these mold segments could be reversed inaccordance with the broadest principles of the disclosure. First or malemold segment 54 includes a mold core 58 slidably mounted within asurrounding sleeve 60 (FIG. 5). Mold core 58 has an end or tip 62contoured for compression molding the inside surfaces of a closure shellin the embodiment of FIGS. 1-5 (and the embodiment of FIGS. 6A-6B). Afirst or outer tube 64 extends coaxially through the hollow interior ofmold core 58 forming a first annular passage between the exteriorsurface of tube 64 and the interior surface of core 58. A second tube orother passage 66 extends through the interior of tube 64, preferablycoaxially with tube 64 and core 58, forming a second annular passagebetween the exterior surface of tube 66 and the interior surface of tube64. The second annular passage between tubes 64, 66 is coupled at amanifold block 68 to a coolant inlet fitting 70. Likewise, the firstannular passage between tube 64 and core 58 is coupled at manifold block68 to a coolant outlet fitting 72. (The “inlet” and “outlet” functionscan be reversed.) Thus, coolant can be fed from fitting 70 through thesecond passage between tubes 64,66 to the tip 62 of core 58, and thencethrough the first passage between tube 64 and core 58 to outlet fitting72. An inlet 74 on manifold block 68 is coupled to the interior of tube66, and can be connected to a source of compressed air for example toassist stripping of closure shells from core tip 62. Manifold block 68preferably is mounted on the radially inner end of mold core 58—i.e.,the end opposite from core tip 62.

A stripper sleeve 76 (FIGS. 3B, 4B and 5) surrounds sleeve 60 and isslidably supported by a bearing 78 within support 46. A cap 80 issecured to support 46, and a coil spring 82 is captured in compressionbetween cap 80 and a washer 84 slidably disposed within support 46 inabutment with the inner end of stripper sleeve 76. Thus, spring 82biases stripper sleeve 76 toward the second or female mold segment 56 ofeach mold 52. When the mold is open, washer 84 abuts a surface 85 withinsupport 46 to limit outward movement of stripper sleeve 76 over core 58.A second coil spring 86 (FIGS. 3C, 4C and 5) is captured in compressionbetween manifold block 68 and an abutment 88 coupled to the end ofsleeve 60. Thus, core 58 is biased by spring 86 inwardly against sleeve60. Each support 44 (FIGS. 3C and 4C) has an interior pocket 90 thatopens radially outwardly toward and in alignment with the associatedfirst mold segment 54. A coil spring 92 is captured in compressionwithin each pocket 90 and engages an extension 94 coupled to an abutment88 on sleeve 60. Thus, as pressure to form the closure shell or linerpushes on core 56, core 56 pushes against sleeve 60, which pushesagainst spring 92 to maintain forming pressure on the melt. (Coilsprings 92 can be replaced by fluid springs.) Within pocket 90, spring92 engages a plate 96 that is coupled to an adjustment screw 98 forindividually adjusting the force applied by each spring 92.

Second or female mold segment 56 (FIGS. 3B, 4B and 5) preferablyincludes a cavity-forming insert 100 having an extension 101 thatreceives a screw 103 removably to mount the insert on a support block102. Blocks 102 are removably mounted on crossbar 50 by screws 105(FIGS. 3B and 4B). Block 102 has coolant passages 106 that communicatein the illustrated embodiment with lateral passages 108,110 in crossbar50, and thence to longitudinal radial passages 112,114 in rod 40. Asbest seen in FIG. 3D, passages 112,114 in rod 40 are connected tofittings 116,118 for circulation of coolant through rod 40, crossbar 50and block 102 to cool mold cavity inserts 100. It will be noted in FIG.3D that fittings 116,118 extend through a slot 120 in spoke 38 to permitradial movement of rod 40 with respect to spoke 38.

A cam follower roller 122 (FIGS. 1, 2, 3A and 4A) is rotatably mountedon a leg 124 that extends radially outwardly from crossbar 50.(Directional words such as “radially,” “laterally,” “outwardly,”“inwardly” and “tangentially” are employed by way of description and notlimitation with respect to the horizontal axis of rotation of thewheel.) Leg 124 is offset from the axis of rod 40 on which crossbar 50is mounted so that cam follower roller 122 is aligned with the axis ofrod 40. Each cam follower roller 122 on each crossbar 50 thus isassociated, in the illustrated exemplary embodiment, with two molds 52located on opposite sides of wheel 22. A cam 126 preferably is disposedalong the lower arc of the periphery of wheel 22, as best seen in FIGS.2 and 2A, for engaging cam follower rollers 122 in sequence as wheel 22rotates around its horizontal axis. During counterclockwise rotation ofwheel 22, in the orientation of FIG. 2, follower rollers 122 of eachpair of molds 52 in sequence are engaged and captured by cam 126 to pullsecond mold segments 56 outwardly and downwardly away from first moldsegments 54. When each mold in turn is fully open, molded parts orarticles are removed from the mold cavities by a suitable part removalmechanism 128 (FIG. 1). A new mold charge is then placed within eachmold cavity by a suitable charge placement apparatus 130. As wheel 22continues rotation, second mold segments 56 in sequence are movedupwardly and inwardly to their closed positions with respect to firstmold segments 54 by the counterclockwise end of cam 126, again in theorientation of FIG. 2. Molded article removal mechanism 128 and moldcharge placement apparatus 130 may be of any suitable types. Forexample, mold charge placement apparatus 130 may be a disk-typeapparatus of the type illustrated in U.S. Pat. No. 5,603,964. As analternative, exemplary mold charge placement devices 130 and molded partremoval devices are discussed in detail in connection with FIGS. 14-22.Hydraulic, pneumatic or electric actuators could be used on each spoke38, instead of cam 126, to move the second mold segment radiallyinwardly or outwardly.

Referring now to FIGS. 1, 3D and 4D, each spoke 38 preferably carries alatch 132 for locking the mold sections to each other in the fullyclosed position so that there is no need for cam 126 to extend entirelyaround the periphery of wheel 22. One embodiment of this latch 132 isillustrated in FIGS. 3D and 4D. Each latch 132 includes a slide pin 134that is slidably mounted in bearings 136 carried by spoke 38. A camfollower roller 138 is carried at the end of slide pin 134 forengagement with a cam 140 (FIG. 3D) disposed in stationary position withrespect to wheel 22. A bridge 142 extends radially outwardly from pin134, and a latch pin 144 is carried by bridge 42. Pin 144 is parallel topin 134 and extends through an opening 146 in spoke 38 in alignment witha pocket 148 in rod 40. Thus, when cam 140 moves pins 134,144 into thelocked position illustrated in FIG. 3D, latch pin 144 extends intopocket 148 and locks rod 40 with respect to spoke 38. Inasmuch as thesecond or female mold segments are mounted on rod 40 while the first ormale mold segments are mounted on spoke 38, the mold segments therebyare locked in the closed position. The latch preferably remains lockedduring a major portion of rotation of wheel 22, such as from about the5:00 position in FIG. 2 counterclockwise to about the 7:00 position, atwhich point another cam pulls pin 44 out of engagement with pocket 148so that the second or female mold cavity may be pulled radiallyoutwardly by cam 126 as previously described.

Another embodiment of the latch 132 is shown in FIGS. 2 and 23. A pin420 is mounted on support 44 adjacent to each rod 40. Each pin 420pivots around an axis perpendicular to rod 40, such as parallel to theaxis of wheel rotation. An arm 422 is coupled to pivot with each pin420. A pair of cam rollers 424, 426 are mounted on arm 422 at positionsspaced from each other and from pin 420. Arm 422 has a slot 428 thatcaptures a screw 430 secured to support 44. Slot 428 and screw 430define stops for rotation of pin 420 and arm 422 in both directions. Pin420 has a flat 432 that selectively registers with rod 40. In thepositions illustrated in FIG. 23, and in FIG. 2 counterclockwise fromabout the 5:30 position to about the 7:00 position, pin 420 is rotatedinto a pocket 434 on rod 40 to lock rod 40 against movement, and therebyto lock the mold sections to each other. From about the 7:00 position toabout the 5:30 position in FIG. 2, pin 420 is pivoted by cam rollers424,426 so that flat 432 registers with rod 40, so that the rod is freeto slide and the mold sections can be opened and closed.

As the second or female mold segment is pulled away from the first ormale mold segment, downwardly in the embodiment illustrated in FIGS.3A-5, this motion of the second or female mold segment strips the moldedpart from the first or male mold segment in this embodiment. Referringin particular to FIGS. 3A-3B and 4A-4B, a collar 150 is seated in arecess 152 adjacent to the radially outer end of each stripper sleeve76. A pair of rods 154 extend from each collar 150 through associatedslide passages in crossbar 50 and carry associated abutment collars 156disposed radially outwardly of the crossbar. As second mold segment 56and crossbar 50 are pulled by cam 126 away from first mold segment 54,crossbar 50 approaches abutment collars 56. When crossbar 50 has beenpulled far enough away from first mold segment 54 to abut collars 156,further motion of crossbar 50 pulls stripper sleeve 76 along sleeve 60and core 58 toward the second mold segment so as to push or strip themolded closure shell from core tip 62. It will be noted in FIGS. 3A and4A in particular that there preferably is lost motion between crossbar50 and abutment collars 156 to ensure that second mold segment 56 hascleared core tip 62 before moving stripper sleeve 76 to strip the partfrom the core trip. Each spring 82 (FIGS. 3B, 4B and 5) biases theassociated stripper sleeve 76 toward second mold segment 56 so as toassist stripping of the molded closure shell. In this connection, assecond mold segment 56 is closed by cam 126, the open edge of cavityinsert 100 preferably engages the opposing end of stripper sleeve 76 andpushes the stripper sleeve against the force of coil spring 82. Abutmentcollars 156 preferably are adjustably slidably positionable on rods 154to adjust the amount of lost motion between crossbar 50 and strippersleeve 76 to a desired level. Crossbar 50, rods 154 and stripper sleeves76 prevent rotation of rod 40 within spoke 38.

Cam 126 may comprise a single solid cam structure, but preferablyincludes an over-pressure release as shown in FIGS. 2 and 2A. In theembodiment of FIGS. 2 and 2A, cam 126 includes a first or upstream camportion 180 (with respect to the direction of wheel rotation). First camportion 180 preferably is mounted in fixed position on a machine bed184. A second or downstream cam portion 182 is pivotally mounted by apin 186 to the downstream end of first cam portion 180. First camportion 180 has a cam surface 188 that increases in radius with respectto the axis of rotation of wheel 22 for opening the molds in sequence,while second cam portion 182 has a cam surface 190 of decreasing radiuswith respect to the wheel axis for engagement by rollers 122 to closethe molds in sequence.

Second cam portion 182 preferably is held in position by a releasablelatch 200, which opens in the event of excessive force on cam portion182. Latch 200 preferably includes a latch arm 202 pivotally coupled atone end to machine bed 184 and having a second end with a pocket 204that releasably captures a detent 206, which preferably is disposed atthe downstream end of second cam portion 182. Latch arm 202 is biasedtoward second cam portion 182 by a spring 208, which may comprise afluid spring (e.g., air or oil), as shown or a suitable mechanicalspring. Thus, in the event of excess force on cam portion 182, such asin the event excess plastic in the mold cavity, detent 206 moves out ofpocket 204 and moves to the position shown in phantom against a stop209. Wheel 22 continues to rotate with the mold segments open. Anextension 210 on cam portion 180 captures the open mold segments uponcontinued rotation of wheel 22.

FIGS. 6A-22 illustrate various modifications or elaborations on theembodiment of FIGS. 1-5. Reference numerals in FIGS. 6A-22 that areidentical to those in FIGS. 1-5 indicate correspondingly identical orrelated components.

FIGS. 6A-6B illustrate a modification to the male and female mold toolstack of FIGS. 3A-5. First or male mold segment 54 includes a mold core220 that will be described in detail in connection with FIGS. 12-12E.Mold core 220 is surrounded by sleeve 60, which in turn is surrounded bystripper sleeve 76. Stripper sleeve 76 is mounted within support 46 by astripper sleeve body 369 and bearings 78. A cam roller 370 is rotatablymounted on a shaft 372 that is secured to stripper sleeve body 369 byscrews 374. A stripping stop 376 surrounds shaft 372 and is slidable ina slot 378 on support 46. During rotation of wheel 22 (FIGS. 1-2), whenthe mold segments are open, cam roller 370 engages a cam 380 adjacent tothe wheel to move stripper sleeve radially outwardly (downwardly inFIGS. 6A-6B) to strip the molded closure shell off of mold core 220.Thus, in this embodiment, the stripper sleeve is activated by a separatecam 380 rather than by motion of second or female mold segment 56 as inthe prior embodiment. Female mold segment 56, including mold cavity 280,is described in connection with FIGS. 13A and 13B. A spool valve 400(FIG. 6B) is carried by manifold 68 and has an actuator pin 402 coupledto a stripper plate 404 through a spring retainer 406 to feed air underpressure through tube 66 as stripper sleeve 76 is actuated to assiststripping of the closure shell.

FIG. 7 illustrates a machine 160 in accordance with a modifiedembodiment of the disclosure, in which there are two wheels 22 mountedfor rotation on a single shaft 24 driven by a single motor 36. Eachwheel 22 is as previously described in conjunction with FIGS. 1-5 orFIGS. 6A-6B.

FIG. 8 illustrates an exemplary implementation of the present disclosurein a machine 162 for compression molding liners within preformed plasticclosure shells. In this machine, the radially outer second mold section164 includes a nest 166 for receiving premade plastic closure shells 168by means of a suitable shell placement mechanism. Inner first moldsegment 170 includes a core 172 having an end contoured to achieve thedesired contour of the sealing liner molded within shell 168. Othercomponents in FIG. 7 that are analogous to components previouslydiscussed in connection with FIGS. 1-5 have correspondingly identicalreference numerals.

FIGS. 9-10C illustrate a modification to the mold opening/closing cam126 illustrated in FIG. 2. In the embodiment of FIGS. 9-10C, a camdisplacement wheel 192 is provided affirmatively to move or lift moldsection roller 122 from cam portion 180 onto a foreshortened second camportion 182 and thereby reduce the angular rotation of the wheel neededto close the mold sections. Cam displacement wheel 192 preferably isrotatably mounted on cam portion 182 and is coupled to a drive 193coupled to a control 194. Drive 193 may comprise a servomotor, forexample, coupled to a servomotor control 194. Alternatively, drive 193may be a cam drive coupled to wheel drive motor 36 (FIG. 1). Camdisplacement wheel 192 thus is rotated in synchronism with rotation ofwheel 22 to lift or displace cam rollers 122 in sequence from camportion 180 to cam portion 182. Wheels 22, 192 preferably rotate atconstant velocity in synchronism with each other. Drive 193 preferablyis coupled through pivot 186. A gear drive 195 (FIG. 9A) couples pivot186 to wheel 192 to rotate the wheel, preferably at constant velocity.Wheel 192 is rotatably mounted on movable cam portion 182. Camdisplacement wheel 192 reduces the load on the guide bearings on wheel22, as well as the angular wheel displacement required to close themolds.

In the embodiment of FIGS. 9-10C, cam displacement wheel 192 has threeangularly spaced radially extending arms 196. The leading edge 198 ofeach arm 196 (with respect to its counterclockwise direction of rotationof wheel 192 in FIGS. 9 and 10A-C) has a rounded contour to engage andlift a roller 199 cantilevered coaxially with cam roller 122 on eachmold section 56. (FIGS. 10A-10C show only one cam arm 196 forsimplicity.) FIG. 10A illustrates initial engagement or contact of a camarm 196 with a roller 199. As arm 196 rotates (counterclockwise in FIGS.10A-10C), roller 199 moves from the mid portion of edge 196 in FIG. 10Athrough the position of FIG. 10B toward the position of FIG. 10C. InFIG. 10C, roller 199 rests on the tip of arm 196 and roller 122 isplaced on the surface 190 of cam portion 182. Edges 198 in sequence thusare profiled to impart inward motion to mold segments 56 (“inward” withrespect to the axis of mold wheel rotation) without generatingdetrimental dynamic forces on cam portion 182. In one presentlypreferred implementation, cam displacement wheel 192 reduces the timerequired for displacing mold segments 52, in units of degrees ofrotation of wheel 22, by a factor of 60%.

FIG. 11 illustrates a modification to the embodiment of FIG. 9, in whichcam displacement wheel 192 has a single arm 196. The number of armsneeded on the cam displacement wheel depends upon the speed of rotationof wheel 22 and the load placed on wheel 192 by the cam sections insequence.

FIGS. 12-12E illustrate a mold core 220 (FIG. 6A) in accordance withanother aspect and embodiment of the disclosure. Elements in FIGS.12A-12E that are identical or similar to elements previously discussed,particularly in connection with FIG. 6A, are indicated bycorrespondingly identical reference numerals. Mold core 220 includes aforming pin 222 (FIGS. 12 and 12E) having an end wall 224 contoured toform the molded component in question, such as the interior of a closureshell base wall or the interior surface of a sealing liner in accordancewith some preferred implementations of the disclosure. The end 225 ofcore forming pin 222 opposed to end wall 224 forms a hollow interior 226that preferably is concentric with forming pin sleeve 60 (FIGS. 12 and12B). The external surface of end 225 extends radially outwardly fromthe body 227 of the forming pin, and a sleeve 228 (FIGS. 12 and 12D)extends axially from core pin end 225 surrounding body 227. Thus, thereis a first annular passage 230 between sleeve 228 and body 227 offorming pin 222, and a second annular passage 232 between the radiallyouter surface of sleeve 228 and the inner surface of sleeve 60. The endof sleeve 228 preferably is spaced from the interior surface of pin endwall 224, and a ring 234 (FIGS. 12 and 12C) is secured around the end ofsleeve 228. Ring 234 preferably is disposed in an annular pocket withinthe end of sleeve 60. Sleeve 228 can be connected to end 225 and ring234 by any suitable means, such as e-beam welding. The end of sleeve 60has an internal shoulder 244 against which forming pin end wall 224 isseated, and the sleeve and forming pin end wall are joined at 246 (FIG.11), preferably by e-beam welding. Shoulder 244 prevents burn-throughduring welding.

The mold stack embodiment of FIGS. 6A-6B is similar to that of FIGS.12-12E, except that the sleeve 228 is threaded at 442 to sleeve 60 inFIG. 6A, so that there is no need for e-beam welding in FIGS. 6A-6B.

A plurality of radially extending fins or ribs 236 (FIGS. 12 and 12E)preferably are formed on the inner surface of pin end wall 224. Theseribs 236 extend from the outer surface of pin body 227 to a positionadjacent to but spaced from the outer periphery of end wall 224. Thelower surface (“lower” in the orientation of FIGS. 12 and 12C) of ring234 preferably abuts the upper surfaces of ribs 236, so that thechannels between the ribs form coolant passages between ring 234 and pinend wall 224. A circumferential array of angularly spaced axiallyextending ribs 238 (FIGS. 12 and 12B) on the inside surfaces of sleeve60 preferably abut ring 234 in assembly, so that the channels betweenthe ribs form axial coolant passages between ring 234 and sleeve 60. Acircumferential array of angularly spaced radially extending ribs orfins 240 (FIGS. 12 and 12C) on the upper surface of ring 234 (in theorientation of FIGS. 12 and 12C) preferably abut an opposing internalshoulder 242 on sleeve 60 to form radial coolant passages between ring234 and shoulder 242. Thus, coolant preferably is circulated from withintube 64 to interior 226 of forming pin 222, through radially extendingpassages 248 in the forming pin into annular passage 230, axially alongannular passage 230, through the radially extending passages formed byribs 236 between end wall 224 and ring 234, axially through the channelsformed by ribs 238 between ring 234 and sleeve 60, radially inwardlythrough the channels formed by ribs 240 between ring 234 and shoulder242, and thence axially through annular passage 232 to the coolantreturn. (The coolant flow direction less preferably can be reversed.)The cross-sectional area to coolant flow preferably is at a minimum inthe axial channels formed by ribs 238 between ring 234 and sleeve 60 tomaximize the heat transfer in this area.

In accordance with another aspect of the present disclosure, forming pin222 may have a concentric axial passage 250 (FIGS. 12 and 12E) thatextends from interior 226 to the end face 252 of end wall 224. A poppetvalve 254 (FIG. 12) has an axially extending cylindrical body 256 thatextends through passage 250, and an enlarged conical head 258 adjacentto end face 252. A coil spring 260 preferably is captured in compressionbetween a retaining ring 262 on valve body 256 and an opposing axiallyfacing surface 264 on pin body 227 within interior 226. Thus, spring 260normally holds valve 254 in the closed position illustrated in FIG. 12.Air tube 66, which preferably is concentrically disposed within coolanttube 64, is coupled to a collar 266 disposed within hollow interior 226of core pin 222 between openings 248 and valve 254. A resilient sealingring 268 preferably is disposed within a channel 270 on collar 266 insealing engagement with the opposed interior surface of pin interior226. Collar 266 with sealing ring 268 cooperates with the hollowinterior of forming pin 222 to form a sealed air cavity 272 that isconnected to air tube 66. When tube 66 (or any other suitable passage)is supplied with air under pressure (e.g., by spool valve 400 in FIG.6B), poppet valve 254 moves outwardly against the force of spring 260.This bodily movement of the poppet valve not only itself assistsstripping of molded articles from end of core pin 220, but also feedsair under pressure through end wall 224 further to assist stripping ofthe molded articles. In this connection, it will be recognized thatpoppet body 256, 258 could be actuated mechanically, such as by a rod,rather than by air pressure.

FIGS. 13A and 13B illustrate a mold cavity 280 in accordance with yetanother aspect of the present disclosure. Mold cavity 280 preferably isdisposed in a pocket 282 on crossbar 50 (or other suitable mold supportstructure). Coolant feed and return passages 108,110 in crossbar 50 openat the axially facing bottom surface 284 of pocket 282. Mold cavity 280preferably includes a mold cavity insert 286 secured within a moldcavity seat 288. Mold cavity seat 288 preferably is cup-shaped, havingan axially facing base 290 opposed to bottom surface 284 of pocket 282,and an annular rim 292 with a radially outwardly facing surface opposedto the radially inwardly facing surface of pocket 282. Base 290 of seat288 has a first opening 291 that opens to coolant passage 108 in bar 50.Opening 291 communicates through passage 296 and a central passage 293to a cup-shaped space 295 between the upper surface of seat 288 and theundersurface of insert 286. This cup-shaped space 295 communicatesaround the edge of seat 288 with an annular space 297 between the outerperiphery of seat 288 and the inner periphery of pocket 282. This space297 connects through a passage 294 with an opening 299 in base 290, andthence to coolant passage 110 in bar 50. Seat 288 extends at 101 forsecurement to crossbar 50 by screw 103, as previously described. Cavityinsert 286 preferably is generally cup-shaped, having a body 298 withinrim 292 of seat 288, and a radially outwardly extending lip or flange300 that overlies the end of seat 288. Rim 300 is secured to crossbar 50by a cavity retaining ring 302. Thus, coolant can circulate from passage108 in crossbar 50 through opening 291 and passage 296 in seat base 290,through passage 293 to space 295, through passages 297 and 294, andthrough opening 299 to passage 110 in bar 50. (Coolant flow could be inthe reverse direction.)

In accordance with a preferred feature of this aspect of the disclosure,cavity insert 286 and seat 288 are rotatable conjointly and bodilywithin pocket 282 of crossbar 50 selectively to move cavity 280 betweenthe position illustrated in FIGS. 13A and 13B for permitting circulationof coolant, and an angularly spaced position for blocking circulation ofcoolant. A key 440 (FIG. 13A) couples cavity insert 286 to seat 288 sothat the insert and seat rotate together. For this purpose, indicia 312preferably are provided on insert rim 300 and retaining ring 302 toindicate whether mold cavity 280 is open or closed to coolantcirculation. Pockets 314 or the like preferably are provided in insertrim 300 for cooperation with a suitable tool to rotate the cavitybetween the open and closed positions for coolant circulation. Thus,ring 302 may be loosened and the cavity insert and seat rotatedconjointly so that openings 291, 299 in seat 288 no longer register withpassages 108, 110 in bar 50.

FIGS. 14-18 illustrate a mold charge placement apparatus 130 (FIG. 1) inaccordance with another aspect of the present disclosure. Mold chargeplacement apparatus 130 in FIGS. 14-18 includes a plate 320, preferablycircular, coupled to a collar 322 for rotation around a first axiscoaxial with plate 320 and collar 322. This axis of rotation preferablyis a vertical axis in one preferred implementation in combination with amold wheel 22 that rotates around a horizontal axis. It will berecognized that wheel 22 and mold sections 56 carried thereby areillustrated only schematically in FIGS. 14-18. It will be noted thatmold charge placement apparatus 130 can be used equally as well incombination with a vertical axis carousel-type compression moldingmachine, in which the mold cavities 56 are presented horizontally insequence adjacent to the periphery of plate 320. Placement apparatus 130can be used for placing mold charges for compression molding closureshells (FIGS. 1-6B) or for compression molding lines in premade shells(FIG. 8).

At least one mold charge cutter and placement mechanism 324 is disposedat the periphery of wheel 320 for severing mold charges from an extrudernozzle 325, transporting the mold charges to mold sections 56 insequence and placing the mold charges into the mold sections. In theillustrated embodiment, there are a pair of mold charge cutting andplacement mechanisms 324 positioned on diametrically opposite sides ofplate 320. A greater number of mechanisms 324 can be placed around plate320, preferably at equal angular increments. Mechanisms 324 preferablyare identical in construction. Each mechanism 324 preferably includes abearing block 326 mounted adjacent to the periphery of plate 320, and adriven shaft 328 that extends through bearing block 326 for rotationaround a second axis perpendicular to the axis of rotation of plate 320.The axes of rotation of driven shafts 328 preferably are colinear. Anarm 330 extends from the end of each shaft 328 at an angle to the axisof shaft rotation, preferably perpendicular to the axis of shaftrotation. A radially outwardly opening hollow cup 332 is mounted at theend of each arm 330. Thus, each cup 332 rotates around the axis of shaft328, and shafts 328 are rotated around the axis of plate 320. A knifeblock 334 is mounted on each bearing block 332 in this embodiment. Acutter blade or knife 336 extends from each block 334 over shaft 328 andat an angle to the axis of shaft 328. Cutter blades 336 passed insequence beneath the outlet of nozzle 326 to sever a mold charge 338from nozzle 325 as the associated cup 332 is positioned beneath thenozzle.

The inner end of each shaft 328 is coupled to a gear 340. Gears 340 inturn are coupled to a gear 342 that is mounted on the end of a driveshaft 344 that extends through collar 322 coaxially with the collar.Thus, rotation of drive shaft 344 is imparted by gears 340, 342 todriven shafts 328, arms 330 and cups 332. Collar 322 and drive shaft 344are coupled to suitable means 346 for controlling rotation of the collarand drive shaft around the first axis. These control means 346 areillustrated in FIG. 14 as comprising a first motor 348 coupled to collar322 and a second motor 350 coupled to drive shaft 344. Motors 348, 350are connected to a suitable control 352 for rotating collar 322 andplate 320, and drive shaft 344 and cups 322, in synchronism, butpreferably independently of each other. Motors 348, 350 may compriseindependently controllable servo motors. As an alternative, drive shaft344 and collar 322 could be coupled by suitable gears, pulleys and thelike to drive motor 36 (FIG. 1) for rotating wheel 322.

In operation, mold charges 338 of suitable resin material are severedfrom nozzle 325 by cutter blades 336 as mechanisms 324 pass in turnbeneath nozzle 325. As a mold charge 338 is severed, arm 330 and cup 332preferably are oriented vertically upwardly (schematically in FIG. 15)to receive the severed mold charge. Continued rotation of shaft 328, arm330 and cup 332 in the direction 360 (from the position shown in solidlines in FIG. 15, through the positions of FIGS. 14 and 16, to theposition of FIG. 17 and in phantom in FIG. 15) transports mold charge338 to a downwardly oriented position, at which point cup 332 and moldcharge 338 are disposed within a mold section 56 for placing the moldcharge. Surface tension between the molten charge 338, and cup 332 andmold section 56, can be used to hold and transfer the mold charge.However, capture, transport and release of the mold charge morepreferably are assisted by a control 354 (FIG. 15) coupled to each cup332 through the associated shaft 328 and arm 330. Control 354selectively applies vacuum to cup 332 for capturing and holding severedmold charge 338 within the cup until the cup is disposed within a moldsection 56, and selectively applies air under pressure through shaft328, arm 330 and cup 332 to assist release and placement of mold charge338 within mold section 56. Thus, each mold charge 338 is placedaffirmatively within a mold section 56, so that placement of the moldcharge is controlled to enhance flow of material during the compressionmolding operation. This controlled charge placement may be contrastedwith prior art techniques, which typically involve free-fall of the moldcharge into the mold section, sometimes assisted by air pressure and/orvertical acceleration of the placement mechanism at the time of release,which can result in non-ideal placement of the mold charge in the moldsection and non-uniform flow of material during compression molding.

FIG. 16 illustrates initial entry of mold charge placement arm 330 andcup 332 into a mold section 56 as wheel 22 rotates in the direction 356,plate 320 rotates in the direction 358 and shaft 328 rotates in thedirection 360. Further rotation of wheel 22, shaft 328 and plate 320bring arm 330 to the vertical orientation illustrated in FIGS. 15 and17, at which point the mold charge is released into the mold section.Further rotation begins to remove arm 330 and cup 332 from section 56,as illustrated in FIG. 18. It will be noted that the speed of rotationof plate 358 is such that arm 330 and cup 332 are removed from moldsection 56 while wheel 22 continuously rotates and without interferenceof the arm and cup with the edges of cavity 56. Plate 320 preferablyrotates in the direction 358 at constant angular velocity, and shafts328, arms 330 and cups 332 preferably rotate in the direction 360 atconstant angular velocity. Wheel 22 preferably rotates in the direction356 at constant angular velocity. It will be noted in FIG. 14 that, whenone of the cups 332 is in a charge placement position in a mold section56, the cup 332 on the opposing side of plate 320 is also in a downwardorientation. Thus, during machine start-up, charge 338 can be retainedin cup 332 rather than placed in mold section 56, and then ejected forscrap or recycle on the opposing side of plate 320.

FIGS. 19-22 illustrate another exemplary mold charge placement apparatus130 (FIG. 2) in accordance with the present disclosure. Referencenumerals in FIGS. 19-22 that are identical to those in FIGS. 14-18illustrate identical or related components. The discussion of FIGS.19-22 will be directed primarily to the differences between theembodiment of FIGS. 19-22 and that of FIGS. 14-18.

In the embodiment of FIGS. 19-22, extruder nozzle 325 is parallel to butlaterally offset from the axis of sleeve 322 and shaft 344. A pelletcutter knife 392 is coupled to a shaft 394 for rotation along a plate396 over the outlet of nozzle 325. Sleeve 322 and shaft 394 are coupledby a belt 345 to motor 346. Shaft 344 is stationary—i.e., does notrotate—in this embodiment. Shaft 344 is coupled to frame 436 by amechanism 438 (FIG. 21) for adjusting the timing of shaft 344 and gear342 relative to sleeve 322 and plate 320. Motor 346 is connected to asuitable control 352 for rotating collar 322 and plate 320, and driveshaft 394 and blade 392, in synchronism with wheel 22. Motor 346 maycomprise an independently controllable servo motor. As an alternative,drive shafts 344, 394 could be coupled by suitable gears, pulleys andthe like to drive motor 36 (FIGS. 1 and 2). Hot melt from an extruder isfed to nozzle 325 by a metering pump 382 (FIG. 17), a passage 384 and adiverter gate 386. Diverter gate 386 is coupled by an arm 388 to acylinder or actuator 390.

In operation, mold charges of suitable resin material are severed fromnozzle 325 by cutter knife 336 as mechanisms 324 pass in turn overnozzle 325. As the mold charge is severed, arm 330 and cup 332preferably are oriented vertically downwardly to receive the severedmold charge. Continued rotation of shaft 328, arm 330 and cup 332transports the mold charge to a downwardly oriented position at whichcup 332 and mold charge 338 are disposed within a mold section 56 forplacing the mold charge. Surface tension between the molten charge andcup 332 and the mold section can be used to hold and transfer the moldcharge. However, capture, transport and release of the mold charge morepreferably are assisted by a control 354 (FIG. 15) coupled to each cup332 through the associated shaft 328 and arm 330. Control 354selectively applies vacuum to cup 332 for capturing and holding severedthe mold charge within the cup until the cup is disposed within a moldsection 56, and selectively applies air under pressure through shaft328, arm 330 and cup 332 to assist release and placement of the moldcharge within mold section 56. Thus, each mold charge is placedaffirmatively within a mold section 56, so that placement of the moldcharge is controlled to enhance flow of material during the compressionmolding operation.

FIGS. 1, 19 and 20 also illustrate an example of molded part removalapparatus 128. A chute 410 is positioned beneath mold segment 54 in theopen position of the mold. Stripper sleeve 76 (FIG. 6A, for example)strips molded closure shells from the male mold core onto chute 410. Oneor more fingers 412 are carried by plate 320 of the mold chargeplacement mechanism to engage the molded closure shell on chute 410 andpush the shell along the chute.

In the various disclosed embodiments, the first or inner mold segment ismounted against a suitable spring to control mold cavity pressure whenthe mold is closed. However, it also is contemplated that the first moldsegments could be coupled to cams or hydraulics, for example, to moveradially inwardly as the second mold segments are moved radiallyoutwardly. This modification may be useful for molding plastic articlesthat are very long in the radial direction of the mold wheel.

Mold charge placement apparatus 130 and mold charge removal apparatus128 in FIGS. 1 and 14-22 are the subject of U.S. patent application Ser.No. 11/156,115. Cam 126 and modifications in FIGS. 2, 2A and 9-11 arethe subject of U.S. patent application Ser. No. 11/156,114. Mold core 54(FIGS. 3B-3C, 4B-4C and 5) and 220 (FIGS. 6A-6B and 12-12E), and moldcavity 100 (FIGS. 3B, 4B and 5), 220 (FIG. 6A) and 280 (FIGS. 13A and13B) are the subject of U.S. patent application Ser. No. 11/155,354.

There thus have been disclosed a machine and method for compressionmolding plastic articles, which fully satisfy all of the objects andaims previously set forth. The disclosure has been presented inconjunction with several presently preferred embodiments, and a numberof additional modifications and variations have been discussed. Othermodifications and variations readily will suggest themselves to personsof ordinary skill in the art. The disclosure is intended to embrace allsuch modifications and variations as fall within the spirit and broadscope of the appended claims.

1. A method of compression molding plastic articles, which includes thesteps of: (a) providing a wheel mounted for rotation around a horizontalaxis and a plurality of angularly spaced molds disposed around saidwheel, each of said molds including a first mold segment and a secondmold segment disposed radially outwardly of said first mold segment, (b)rotating said wheel around said horizontal axis, (c) as said wheelrotates, radially moving each second mold segment in sequence withrespect to the associated first mold segment between a radially innerclosed position with said first mold segment and a radially outer openposition spaced from the associated first mold segment, (d) with saidmold segments in said open position, removing a molded article from saidmold and placing a mold charge into said mold, (e) closing said moldsegments as said wheel rotates to compression mold plastic articlesbetween said mold segments, and (f) using radial motion of said secondmold segment in said step (c) to remove the molded article from the moldin said step (d), wherein each of said first mold segments includes amale mold segment having a core and a stripper sleeve surrounding saidcore, and wherein said step (f) is carried out by operatively couplingat least one abutment to said stripper sleeve and spaced from saidsecond mold segment in said closed position of said molds, said abutmentbeing disposed for engagement by said second mold segment during motionof said second mold segment toward said open position to strip a moldedpart from said core as said second mold segment is moved radiallyoutwardly toward said open position such that there is lost motionbetween said second mold segment and said abutment to allow said secondmold segment to clear said mold core before initiating motion of saidstripper sleeve.
 2. The method set forth in claim 1 wherein said step(c) is carried out by positioning a cam adjacent to said wheel forengagement with said molds to open and close said molds in sequence assaid wheel rotates.
 3. The method set forth in claim 2 wherein said step(c) includes latching said mold segments to each other when said moldsegments are in said closed position.